
<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
  <head>
    <meta charset="utf-8" /><meta name="generator" content="Docutils 0.17.1: http://docutils.sourceforge.net/" />

    <title>Concrete Objects Layer &#8212; Python 3.9.6 documentation</title>
    <link rel="stylesheet" href="../_static/pydoctheme.css" type="text/css" />
    <link rel="stylesheet" href="../_static/pygments.css" type="text/css" />
    
    <script type="text/javascript" id="documentation_options" data-url_root="../" src="../_static/documentation_options.js"></script>
    <script type="text/javascript" src="../_static/jquery.js"></script>
    <script type="text/javascript" src="../_static/underscore.js"></script>
    <script type="text/javascript" src="../_static/doctools.js"></script>
    <script type="text/javascript" src="../_static/language_data.js"></script>
    
    <script type="text/javascript" src="../_static/sidebar.js"></script>
    
    <link rel="search" type="application/opensearchdescription+xml"
          title="Search within Python 3.9.6 documentation"
          href="../_static/opensearch.xml"/>
    <link rel="author" title="About these documents" href="../about.html" />
    <link rel="index" title="Index" href="../genindex.html" />
    <link rel="search" title="Search" href="../search.html" />
    <link rel="copyright" title="Copyright" href="../copyright.html" />
    <link rel="next" title="Type Objects" href="type.html" />
    <link rel="prev" title="Old Buffer Protocol" href="objbuffer.html" />
    <link rel="canonical" href="https://docs.python.org/3/c-api/concrete.html" />
    
      
      
    

    
    <style>
      @media only screen {
        table.full-width-table {
            width: 100%;
        }
      }
    </style>

    <link rel="shortcut icon" type="image/png" href="../_static/py.png" />
    
    <script type="text/javascript" src="../_static/copybutton.js"></script>
    
     


  </head><body>
  
    <div class="related" role="navigation" aria-label="related navigation">
      <h3>Navigation</h3>
      <ul>
        <li class="right" style="margin-right: 10px">
          <a href="../genindex.html" title="General Index"
             accesskey="I">index</a></li>
        <li class="right" >
          <a href="../py-modindex.html" title="Python Module Index"
             >modules</a> |</li>
        <li class="right" >
          <a href="type.html" title="Type Objects"
             accesskey="N">next</a> |</li>
        <li class="right" >
          <a href="objbuffer.html" title="Old Buffer Protocol"
             accesskey="P">previous</a> |</li>

    <li><img src="../_static/py.png" alt=""
             style="vertical-align: middle; margin-top: -1px"/></li>
    <li><a href="https://www.python.org/">Python</a> &#187;</li>
    

    <li>
      <a href="../index.html">3.9.6 Documentation</a> &#187;
    </li>

          <li class="nav-item nav-item-1"><a href="index.html" accesskey="U">Python/C API Reference Manual</a> &#187;</li>
    <li class="right">
        

    <div class="inline-search" style="display: none" role="search">
        <form class="inline-search" action="../search.html" method="get">
          <input placeholder="Quick search" type="text" name="q" />
          <input type="submit" value="Go" />
          <input type="hidden" name="check_keywords" value="yes" />
          <input type="hidden" name="area" value="default" />
        </form>
    </div>
    <script type="text/javascript">$('.inline-search').show(0);</script>
         |
    </li>

      </ul>
    </div>    

    <div class="document">
      <div class="documentwrapper">
        <div class="bodywrapper">
          <div class="body" role="main">
            
  <section id="concrete-objects-layer">
<span id="concrete"></span><h1>Concrete Objects Layer<a class="headerlink" href="#concrete-objects-layer" title="Permalink to this headline">¶</a></h1>
<p>The functions in this chapter are specific to certain Python object types.
Passing them an object of the wrong type is not a good idea; if you receive an
object from a Python program and you are not sure that it has the right type,
you must perform a type check first; for example, to check that an object is a
dictionary, use <a class="reference internal" href="dict.html#c.PyDict_Check" title="PyDict_Check"><code class="xref c c-func docutils literal notranslate"><span class="pre">PyDict_Check()</span></code></a>.  The chapter is structured like the
“family tree” of Python object types.</p>
<div class="admonition warning">
<p class="admonition-title">Warning</p>
<p>While the functions described in this chapter carefully check the type of the
objects which are passed in, many of them do not check for <code class="docutils literal notranslate"><span class="pre">NULL</span></code> being passed
instead of a valid object.  Allowing <code class="docutils literal notranslate"><span class="pre">NULL</span></code> to be passed in can cause memory
access violations and immediate termination of the interpreter.</p>
</div>
<section id="fundamental-objects">
<span id="fundamental"></span><h2>Fundamental Objects<a class="headerlink" href="#fundamental-objects" title="Permalink to this headline">¶</a></h2>
<p>This section describes Python type objects and the singleton object <code class="docutils literal notranslate"><span class="pre">None</span></code>.</p>
<div class="toctree-wrapper compound">
<ul>
<li class="toctree-l1"><a class="reference internal" href="type.html">Type Objects</a><ul>
<li class="toctree-l2"><a class="reference internal" href="type.html#creating-heap-allocated-types">Creating Heap-Allocated Types</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="none.html">The <code class="docutils literal notranslate"><span class="pre">None</span></code> Object</a></li>
</ul>
</div>
</section>
<section id="numeric-objects">
<span id="numericobjects"></span><h2>Numeric Objects<a class="headerlink" href="#numeric-objects" title="Permalink to this headline">¶</a></h2>
<div class="toctree-wrapper compound" id="index-0">
<ul>
<li class="toctree-l1"><a class="reference internal" href="long.html">Integer Objects</a></li>
<li class="toctree-l1"><a class="reference internal" href="bool.html">Boolean Objects</a></li>
<li class="toctree-l1"><a class="reference internal" href="float.html">Floating Point Objects</a></li>
<li class="toctree-l1"><a class="reference internal" href="complex.html">Complex Number Objects</a><ul>
<li class="toctree-l2"><a class="reference internal" href="complex.html#complex-numbers-as-c-structures">Complex Numbers as C Structures</a></li>
<li class="toctree-l2"><a class="reference internal" href="complex.html#complex-numbers-as-python-objects">Complex Numbers as Python Objects</a></li>
</ul>
</li>
</ul>
</div>
</section>
<section id="sequence-objects">
<span id="sequenceobjects"></span><h2>Sequence Objects<a class="headerlink" href="#sequence-objects" title="Permalink to this headline">¶</a></h2>
<p id="index-1">Generic operations on sequence objects were discussed in the previous chapter;
this section deals with the specific kinds of sequence objects that are
intrinsic to the Python language.</p>
<div class="toctree-wrapper compound">
<ul>
<li class="toctree-l1"><a class="reference internal" href="bytes.html">Bytes Objects</a></li>
<li class="toctree-l1"><a class="reference internal" href="bytearray.html">Byte Array Objects</a><ul>
<li class="toctree-l2"><a class="reference internal" href="bytearray.html#type-check-macros">Type check macros</a></li>
<li class="toctree-l2"><a class="reference internal" href="bytearray.html#direct-api-functions">Direct API functions</a></li>
<li class="toctree-l2"><a class="reference internal" href="bytearray.html#macros">Macros</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="unicode.html">Unicode Objects and Codecs</a><ul>
<li class="toctree-l2"><a class="reference internal" href="unicode.html#unicode-objects">Unicode Objects</a><ul>
<li class="toctree-l3"><a class="reference internal" href="unicode.html#unicode-type">Unicode Type</a></li>
<li class="toctree-l3"><a class="reference internal" href="unicode.html#unicode-character-properties">Unicode Character Properties</a></li>
<li class="toctree-l3"><a class="reference internal" href="unicode.html#creating-and-accessing-unicode-strings">Creating and accessing Unicode strings</a></li>
<li class="toctree-l3"><a class="reference internal" href="unicode.html#deprecated-py-unicode-apis">Deprecated Py_UNICODE APIs</a></li>
<li class="toctree-l3"><a class="reference internal" href="unicode.html#locale-encoding">Locale Encoding</a></li>
<li class="toctree-l3"><a class="reference internal" href="unicode.html#file-system-encoding">File System Encoding</a></li>
<li class="toctree-l3"><a class="reference internal" href="unicode.html#wchar-t-support">wchar_t Support</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="unicode.html#built-in-codecs">Built-in Codecs</a><ul>
<li class="toctree-l3"><a class="reference internal" href="unicode.html#generic-codecs">Generic Codecs</a></li>
<li class="toctree-l3"><a class="reference internal" href="unicode.html#utf-8-codecs">UTF-8 Codecs</a></li>
<li class="toctree-l3"><a class="reference internal" href="unicode.html#utf-32-codecs">UTF-32 Codecs</a></li>
<li class="toctree-l3"><a class="reference internal" href="unicode.html#utf-16-codecs">UTF-16 Codecs</a></li>
<li class="toctree-l3"><a class="reference internal" href="unicode.html#utf-7-codecs">UTF-7 Codecs</a></li>
<li class="toctree-l3"><a class="reference internal" href="unicode.html#unicode-escape-codecs">Unicode-Escape Codecs</a></li>
<li class="toctree-l3"><a class="reference internal" href="unicode.html#raw-unicode-escape-codecs">Raw-Unicode-Escape Codecs</a></li>
<li class="toctree-l3"><a class="reference internal" href="unicode.html#latin-1-codecs">Latin-1 Codecs</a></li>
<li class="toctree-l3"><a class="reference internal" href="unicode.html#ascii-codecs">ASCII Codecs</a></li>
<li class="toctree-l3"><a class="reference internal" href="unicode.html#character-map-codecs">Character Map Codecs</a></li>
<li class="toctree-l3"><a class="reference internal" href="unicode.html#mbcs-codecs-for-windows">MBCS codecs for Windows</a></li>
<li class="toctree-l3"><a class="reference internal" href="unicode.html#methods-slots">Methods &amp; Slots</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="unicode.html#methods-and-slot-functions">Methods and Slot Functions</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="tuple.html">Tuple Objects</a></li>
<li class="toctree-l1"><a class="reference internal" href="tuple.html#struct-sequence-objects">Struct Sequence Objects</a></li>
<li class="toctree-l1"><a class="reference internal" href="list.html">List Objects</a></li>
</ul>
</div>
</section>
<section id="container-objects">
<span id="mapobjects"></span><h2>Container Objects<a class="headerlink" href="#container-objects" title="Permalink to this headline">¶</a></h2>
<div class="toctree-wrapper compound" id="index-2">
<ul>
<li class="toctree-l1"><a class="reference internal" href="dict.html">Dictionary Objects</a></li>
<li class="toctree-l1"><a class="reference internal" href="set.html">Set Objects</a></li>
</ul>
</div>
</section>
<section id="function-objects">
<span id="otherobjects"></span><h2>Function Objects<a class="headerlink" href="#function-objects" title="Permalink to this headline">¶</a></h2>
<div class="toctree-wrapper compound">
<ul>
<li class="toctree-l1"><a class="reference internal" href="function.html">Function Objects</a></li>
<li class="toctree-l1"><a class="reference internal" href="method.html">Instance Method Objects</a></li>
<li class="toctree-l1"><a class="reference internal" href="method.html#method-objects">Method Objects</a></li>
<li class="toctree-l1"><a class="reference internal" href="cell.html">Cell Objects</a></li>
<li class="toctree-l1"><a class="reference internal" href="code.html">Code Objects</a></li>
</ul>
</div>
</section>
<section id="other-objects">
<h2>Other Objects<a class="headerlink" href="#other-objects" title="Permalink to this headline">¶</a></h2>
<div class="toctree-wrapper compound">
<ul>
<li class="toctree-l1"><a class="reference internal" href="file.html">File Objects</a></li>
<li class="toctree-l1"><a class="reference internal" href="module.html">Module Objects</a><ul>
<li class="toctree-l2"><a class="reference internal" href="module.html#initializing-c-modules">Initializing C modules</a><ul>
<li class="toctree-l3"><a class="reference internal" href="module.html#single-phase-initialization">Single-phase initialization</a></li>
<li class="toctree-l3"><a class="reference internal" href="module.html#multi-phase-initialization">Multi-phase initialization</a></li>
<li class="toctree-l3"><a class="reference internal" href="module.html#low-level-module-creation-functions">Low-level module creation functions</a></li>
<li class="toctree-l3"><a class="reference internal" href="module.html#support-functions">Support functions</a></li>
</ul>
</li>
<li class="toctree-l2"><a class="reference internal" href="module.html#module-lookup">Module lookup</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="iterator.html">Iterator Objects</a></li>
<li class="toctree-l1"><a class="reference internal" href="descriptor.html">Descriptor Objects</a></li>
<li class="toctree-l1"><a class="reference internal" href="slice.html">Slice Objects</a></li>
<li class="toctree-l1"><a class="reference internal" href="slice.html#ellipsis-object">Ellipsis Object</a></li>
<li class="toctree-l1"><a class="reference internal" href="memoryview.html">MemoryView objects</a></li>
<li class="toctree-l1"><a class="reference internal" href="weakref.html">Weak Reference Objects</a></li>
<li class="toctree-l1"><a class="reference internal" href="capsule.html">Capsules</a></li>
<li class="toctree-l1"><a class="reference internal" href="gen.html">Generator Objects</a></li>
<li class="toctree-l1"><a class="reference internal" href="coro.html">Coroutine Objects</a></li>
<li class="toctree-l1"><a class="reference internal" href="contextvars.html">Context Variables Objects</a></li>
<li class="toctree-l1"><a class="reference internal" href="datetime.html">DateTime Objects</a></li>
<li class="toctree-l1"><a class="reference internal" href="typehints.html">Objects for Type Hinting</a></li>
</ul>
</div>
</section>
</section>


          </div>
        </div>
      </div>
      <div class="sphinxsidebar" role="navigation" aria-label="main navigation">
        <div class="sphinxsidebarwrapper">
  <h3><a href="../contents.html">Table of Contents</a></h3>
  <ul>
<li><a class="reference internal" href="#">Concrete Objects Layer</a><ul>
<li><a class="reference internal" href="#fundamental-objects">Fundamental Objects</a></li>
<li><a class="reference internal" href="#numeric-objects">Numeric Objects</a></li>
<li><a class="reference internal" href="#sequence-objects">Sequence Objects</a></li>
<li><a class="reference internal" href="#container-objects">Container Objects</a></li>
<li><a class="reference internal" href="#function-objects">Function Objects</a></li>
<li><a class="reference internal" href="#other-objects">Other Objects</a></li>
</ul>
</li>
</ul>

  <h4>Previous topic</h4>
  <p class="topless"><a href="objbuffer.html"
                        title="previous chapter">Old Buffer Protocol</a></p>
  <h4>Next topic</h4>
  <p class="topless"><a href="type.html"
                        title="next chapter">Type Objects</a></p>
  <div role="note" aria-label="source link">
    <h3>This Page</h3>
    <ul class="this-page-menu">
      <li><a href="../bugs.html">Report a Bug</a></li>
      <li>
        <a href="https://github.com/python/cpython/blob/3.9/Doc/c-api/concrete.rst"
            rel="nofollow">Show Source
        </a>
      </li>
    </ul>
  </div>
        </div>
      </div>
      <div class="clearer"></div>
    </div>  
    <div class="related" role="navigation" aria-label="related navigation">
      <h3>Navigation</h3>
      <ul>
        <li class="right" style="margin-right: 10px">
          <a href="../genindex.html" title="General Index"
             >index</a></li>
        <li class="right" >
          <a href="../py-modindex.html" title="Python Module Index"
             >modules</a> |</li>
        <li class="right" >
          <a href="type.html" title="Type Objects"
             >next</a> |</li>
        <li class="right" >
          <a href="objbuffer.html" title="Old Buffer Protocol"
             >previous</a> |</li>

    <li><img src="../_static/py.png" alt=""
             style="vertical-align: middle; margin-top: -1px"/></li>
    <li><a href="https://www.python.org/">Python</a> &#187;</li>
    

    <li>
      <a href="../index.html">3.9.6 Documentation</a> &#187;
    </li>

          <li class="nav-item nav-item-1"><a href="index.html" >Python/C API Reference Manual</a> &#187;</li>
    <li class="right">
        

    <div class="inline-search" style="display: none" role="search">
        <form class="inline-search" action="../search.html" method="get">
          <input placeholder="Quick search" type="text" name="q" />
          <input type="submit" value="Go" />
          <input type="hidden" name="check_keywords" value="yes" />
          <input type="hidden" name="area" value="default" />
        </form>
    </div>
    <script type="text/javascript">$('.inline-search').show(0);</script>
         |
    </li>

      </ul>
    </div>  
    <div class="footer">
    &copy; <a href="../copyright.html">Copyright</a> 2001-2021, Python Software Foundation.
    <br />

    The Python Software Foundation is a non-profit corporation.
<a href="https://www.python.org/psf/donations/">Please donate.</a>
<br />
    <br />

    Last updated on Jun 28, 2021.
    <a href="https://docs.python.org/3/bugs.html">Found a bug</a>?
    <br />

    Created using <a href="https://www.sphinx-doc.org/">Sphinx</a> 2.3.1.
    </div>

  </body>
</html>